There has so far been proposed a head-mounted image display apparatus for allowing a two-dimensional image, demonstrated on an image display device, to be observed by a viewer as an enlarged virtual image by a virtual-image optical system employing a reflective/transmitting optical device. As typical of this sort of image display apparatus, there is an image display apparatus disclosed in U.S. Pat. No. 5,886,822. With the virtual-image optical system found in the image display apparatus disclosed in the Patent Publication, it is desirable to improve the mounting feeling by arranging the apparatus so as to conform the shape of the face of a user, in particular the shape of the face in the vicinity of his/her eyes. It is also desirable to reduce the thickness of the apparatus in a direction along the field of view and to improve the light utilization efficiency as much as possible.